The present claimed invention relates to an electric power supply system for LED lighting unit suitable for lighting for varieties of optical inspections or mark reading.
Recently LED lighting units have been in heavy usage for optical lighting in order to inspect a fine flaw on a surface of an object or to read a sign such as an alignment mark in accordance with improvement of LED performance. Since each of the LED lighting units varies in a characteristics, an arrangement and a number of an LED element in compliance with its purpose, the LED lighting unit is connected with an electric power supply unit that meets a requirement of a current and a voltage of the LED lighting unit. Further, in case an adjustment range is lowered in use, if the electric power supply unit is used in a rated condition of use without change, there is a problem such that a fine control is difficult.
Generally an electric input connector of a same size specification or an electric output-connector of the same size specification that coincides with the electric input connector is attached to the LED lighting unit and a constant current supply unit respectively in a step of manufacturing the LED lighting unit and the constant current supply unit. The electric power supply unit is desired to verify and set a range to meet a rated condition of use of the LED lighting unit to be used. However, this procedure is troublesome and there is a possibility that time is wasted or malfunction is occurred due to a wrong setting of the range.
There was a technique as described in the following patent document 1 to verify a combination of the lighting unit and the electric power supply unit after connected whether the combination was appropriate or not.
(Patent Document 1)
Patent Laid Open No. 6-94627(Japan)
However, the lighting unit described in the patent document 1 uses an electric filament lamp such as a halogen lamp as a light source and is so arranged that a current considerably smaller than a rated value is passed through the electric power supply unit so as not to actuate the electric filament lamp practically and the light source is specified by measuring resistance peculiar to the filament and then a voltage and a current corresponding to the light source is set. As a result, the technique cannot be applied to the LED because resistance becomes almost zero when a current passes forward.
Varieties of LED lighting units, especially for inspecting an appearance of an article, have been developed in accordance with an LED made to be super powerful and improvement in a range and selectivity of an emission wave length and an electric power supply unit for supplying electric power to the LED systems has also been developed. Accordingly, a proper lighting unit should be selected and combined with a proper electric power supply unit (or an electric power supply tap) in order to obtain appropriate lighting which might otherwise be a cause of malfunction or trouble.
The present claimed invention intends to provide an electric power supply system for LED lighting unit that can recognize a type or a desired operating condition of a lighting unit automatically and supply electric power corresponding to the type or the operating condition when the lighting unit using the LED is connected to a predetermined electric power supply unit.
In case of a conventional LED lighting unit, the present claimed invention further intends to provide an electric power supply system for LED lighting unit that can recognize a type or a desired operating condition of a lighting unit automatically and supply electric power corresponding to the type or the operating condition by being equipped with a simple additional mechanism so as to exemplify a technical idea when the conventional LED lighting unit is connected to a predetermined electric power supply unit.